1. Field of the Invention
The present invention relates generally to an improved gas-fired convection oven, and it relates more particularly to a convection oven having substantially improved heating efficiency over prior art ovens.
2. Description of the Prior Art
A popular type of oven for use in commercial cooking and baking applications is a gas-fired convection oven. The gas-fired convection oven typically includes an insulated enclosure defining a cooking cavity having access in the form of one or more hinged forwardly facing doors. In the rear of the cavity is mounted a motor-operated fan adapted to circulate cavity air across a heat exchanger. The heat exchanger typically comprises a hollow tube constructed to receive a preselected mixture of natural gas and air admitted into the tube from a burner and secondary air supply conduit. When the burner is ignited, heat generating combustion by-products flow into the heat exchanger and air circulated over the heat exchanger walls is directed into the cavity for cooking or baking food products placed therein An example of the foregoing oven is disclosed in U.S. Pat. No. 4,648,377 issued Mar. 10, 1987 to Van Camp and assigned to the assignee hereof. As shown therein, the heat exchanger may consist of a hollow tube positioned proximate the rear wall of the oven cavity with the circulating fan disposed centrally thereof. A shroud may be mounted in front of the heat exchanger such that intake air is admitted to the fan through a central shroud opening and is circulated back into the oven cavity through space provided between the shroud edges and the walls of the oven cavity.
Convection ovens of the foregoing type offer considerable advantages over non-convection devices in that cooking times can be substantially reduced. A forced-air system results in heat transfer to the product by means of turbulent air flow across the product surfaces thereby enhancing the rate of heat transfer to the product. Thus, convection ovens have proved to be an important advancement in the food preparation art. However, a disadvantage of known convection ovens resides in their inability to cook or bake food products with uniform surface characteristics and doneness. Lack of uniformity in surface characteristics or doneness can result, for example, from disparate or unequal pressure zones within the cooking cavity due to air flow characteristics of the fan and cavity. It would therefore be desirable to provide a convection oven which exhibits substantially uniform cooking results. Moreover, it would be further desirable to provide a convection oven having greater heat transfer efficiency than presently known oven units, whereby the oven can be operated with reduced gas consumption and greater energy efficiency.